Cell Recognition And The Immune System Flashcards
what is a cell that can cause illness
antigen presenting cell
what are the 3 types of antigen presenting cells
bacteria
body cell with virus
body cell with cancer
what is an auto immune disease
when the immune system attacks itself
what are two types of auto immune diseases
t1 diabetes
chroness disease
what are the bodies 10 first lines of defense
eyes
ears
nasal cavity
skin
urethra
anus
vagina
stomach
trachea and bronchi
mouth cavity
what are the two varients of physical barriers
physical - skin
chemical - enzymes in tears
what is the second life of defense
non specific - phagocytes
what is the third line of defense
specific - B and T lymphocytes
what type of cells do phagocytes destroy
any foreign cell
where are phagocytes found
blood and they can also go into the tissue
what dilates blood vessels to help phagocytes
histamines
what do lymphocytes respond to
antigen presenting cells
where are all blood cells made
in bone marrow
where are T lymphocytes matured
the thymus gland
what do T cells respond do
antigens on the surface of APC’s
where do B cells mature
bone marrow
whaat do B cells respond to
antigens on the surface of APC’s and free antigens
what type of response is B cells
liquid
what do B cells make
antibodies
how do phagocytes find foreign cells
they are chemically attracted due to a chemical concentration difference (chemo-attraction)
what does the phagocyte do when it locates a foreign cell
engulfs it into a phagosome
what happens to the foreign cell after it has been engulffed by the phagocyte
lysosomes fuse with the phagosome and release lysozymes which hydrolyze the foreign cell
what happens to the foreign cell after it has been hydrolyzed
either exocyted or some broken parts can be reabsorbed if theyre useful
what are pathogens
microorganisms that cause harm to the body
what is an antigen
- a molecule that stimulates a cell response
- large, complex molecules such as glcyoproteins / glycolipids / proteins
what do t cells have on their surface
receptors which will only bind to the antigen of an APC
when does a phagocyte become an APC
when it presents an antigen at its surface from an ingested pathogen, foreign cell or toxin
what happens to a T cells when they bind to a complementary antigen of an APC
they become sensitised and divide (mitosis) to form cloned cells
what can the cloned T cells differentiate into (3)
memory T cells
helper T cells
cytoxic T cells
what is the role of memory T cells
remain in the blood and cause a rapid increase in the number of T cells when re-expoed to the antigen (short term immunity)
what is the role of helper T cells
assist other white blood cells by releasing chemical messangers called cytokines - these stimulate B cells and activate cytoxic T cells and phagocytes
what is the role of cytoxic T cells
destroy tumor cells and cells that are infected with viruses
what type of immunity do B cells provide
humoral immunity (liquid response)
what causes the B cells to activate
if a receptor - antigen complex forms (by the two being complementary and binding)
what do most of the B cell clones differentiate into
plasma cells which make and release antibodies
what do a small number of cloned B cells differentiate into
memory cells which divide raplidly if re-exposed to the antigen
what do antibodies travel through
the blood
what are antibodies
a protein released by a B cell in response to a foreign antiggen
what is the shape of an antibody molecule
Y shaped
how many polypeptide chains make up an antibody
4
2 are large heavy chains
2 are small light chains
what does an antibody have which allows it to bind to one specific antigen
antigen binding site
what bonds hold the antibodies together
di-sulfide
what is the variable region of the antibody
the top of the Y shape
has a different sequence of amino acids
what is the constant portion of the antibody
at the bottm of the y shape
the same sequence of amino acids
what is the binding site of an antibody
the site which is complementary and firts very specifically to a specific antigen
what determines the shape of the binding site
the order of amino acids in the variable region
what does the constant portion of an antibody allow
binding to a receptor
what does the hinge region of the antibody allow
flexibility in binding
what are the two uses of monoclonal antibodies
targetted drug delivery
pregnancy test kits
ELISA
how are monoclonal antibodies used for targetted drug delivery
the chemo drug binds to the monoclonal antibody, that is complementary to the cancer cells antigens (only kills these cells)
what hormone do pregnant women produce in their urine
hCG
what occurs in a pregnancy test if the woman is pregnant (5)
- hCG from urine binds to the 1st monoclonal antibody (mobile), this is also binded to a blue bead
- hCG binds to the 2nd monochlonal antibody (immobile) that is on the pregnancy test
- This will produce the first line if pregnant
- 3rd monoclonal antibody (immobile) binds to the 1st mobile antibody
- will always produce a line (a control)
what is a vaccine
a preparation of antigens from a pathogen, that aim to build immunity against this pathogen
how are vaccines made harmless (4)
- killing the pathogen
- weakening the pathogen (attenuated pathogen)
- using the bacterial toxin
- using genetically modified pathogens
what is the idea of herd immunity
if a significant portion of a population are immune, the disease will find it difficult to spread
what is active immunity
when a person makes antibodies
what are examples of active immunity
when a person is exposed to an infectious disease
when a person is vaccinated
what is passive immunity
when a person is given antibodies
what are examples of passive immunity
when babies are breast fed
when doctors inject antibodies
what does HIV and AIDS stand for
Human immuno deficiency virus
Acquired immune deficiency syndrome
how does HIV spread
person to person bodily fluids:
- sexual intercourse
- infected blood transfusions
- IV drug users sharing needles
- from an infected mother to unborn baby
what is the first step of HIV replication
it attches to CD4 surface receptors on a T helper cell and injects reverse transcriptase and RNA into the cell
what does the rever transcriptase that gets injected into the T helper cell do
uses the HIV’s RNA as a template to make a DNA copy, which is inserted into the host T helper cell’s DNA
what happens to the viral DNA that reverse transcriptase produces
it is transcribed to make viral mRNA and translated to make viral protiens
what do the viral proteins that HIV makes do
these and RNA form new HIV particles which burst out the helper T cell to infect more of them
does the viral proteins leaving the T helper cells damage them
yes, it destroys them which reduces the immune capability of the host
how does HIV lead to AIDS
- drop in T helper cell numbers (cannot stimulate B plasma cells to make antibodies or cytoxic T cells to kill infected cells)
- memory cells are infected and destroyed
- immunity is compromised
- cannot fight off opportunistic infections
does HIV lead to death
no, secondary diseases do
what does the ELISA test stand for
enzyme linked immunoabsorbant assay
what does the ELISA test do
uses antibodies to detect the presence and quantity of a protein in a sample
true or false
the ELISA test can only detect large amounts of a molecule
false, its very sensetive
in the ELISA test, where do you apply the sample of antigens to
a slide or well
what do you add to the well that has the antigens in the ELISA test. why?
plasma sample - if the person is infected, anitbodies specific to the antigen to bind to it
what must you do during the ELISA test after you add the plasma
wash it out to remove antibodies not specific to the antigen
what do you add to the ELISA test after you have added the first plasma / antibody sample
second antibody that has an attached enzyme which will cause a colour change
what must you do after adding the second antibody with the enzyme attatched in the ELISA test, why
wash it out to remove any unattatched enzymes that would cause a false positive
what do you add to the ELISA test after the secon antibody with an enzyme
the substrate which will cause a colour change if the test is positive
why do antibiotics work against bacteria
- they stop the cell wall synthesis
- they stop proteins being made
- they stop nucleic acid synthesis
why dont antibiotics not work against viruses
as they’re non living and they aren’t cells
